The development of methods of detecting and quantifying a biomolecule such as a target biomarker at high sensitivity is regarded as very important in the fields of medical and life sciences, such as in the diagnosis of diseases and the development of new drugs. Representative and widely used is a binding assay based on an antigen-antibody immunoreaction, a DNA hybridization, a receptor reaction or the like, depending on the type of target material, and the presence of a target molecule is determined by means of a signal transducer that converts the binding event with the target molecule into a measurable signal.
A magnetic nanoparticle mediated isolation technique using magnetic force in the binding assay is advantageous because a target biomolecule is obtained in isolation from a suspended solution comprising various impurities or non-target materials, which are mixed together, through a concentrating process (positive isolation) or by removing non-target molecules (negative isolation), thus exhibiting a simplified assay, processing feasibility, high sensitivity, improved specificity, high-throughput screening, and scalability.
A magnetic nanoparticle mediated isolation technique is performed in a manner in which a ligand material that specifically binds to the target molecule is attached to particles, followed by recognizing and bonding of the ligand material to the target molecule in the mixed solution and separation of the magnetic particles using external magnetic force. Here, magnetic particles, suitable for use in a target molecule sensing platform, are required to (i) minimize non-specific adsorption from a variety of non-specific materials in a suspended solution, (ii) maintain the stability of colloidal particles from various biochemical environments, and (iii) facilitate surface bonding of various functional groups. In order to form a non-fouling bio-interface, the particles are preferably hydrophilic and neutral and contain hydrogen bond acceptors. To this end, PEGylation, that is, coating the surface of particles with poly(ethylene glycol) which is one of the biocompatible polymer is to date still considered to be the most successful way to design nanoparticles having a non-fouling bio-interface. The precisely adsorbed PEG layer satisfies the requirements listed above, reduces non-specific adsorption of particles and increases stability.
The present inventors provide a method of manufacturing a superparamagnetic nanocomposite, that is, a superparamagnetic iron oxide nanocomposite, suitable for use in magnetic separation for the detection of a target biomaterial. Thus, the method of manufacturing the superparamagnetic nanocomposite has a higher yield and a high rate without complicated processing than a conventional method of manufacturing a magnetic nanoparticle for magnetic separation and is capable of mass production of the superparamagnetic nanocomposite having excellent properties with uniform size and particle size distribution, high aqueous solution dispersibility and high magnetization and being capable of maintaining superparamagnetism, thereby culminating in the present invention.